Recently, there has been increasing popularity of small format cameras and the color photographic enlargement prints are often formed from a small-sized picture image of color negative films. Therefore, color photographic materials having further improved graininess and resolving power have been desired.
The graininess of a color image can be improved by increasing the number of silver halide grains and by making dyes formed by color development indefinite as described in T. H. James, Theory of the Photographic Process, 4th Ed., pages 620-621. However, the attempt at increasing the number of silver halide grains while maintaining a high photographic sensitivity requires an increase in the amount of coated silver and causes a reduction in resolving power. Thus this attempt is disadvantageous in view of cost and photographic properties.
The attempt at improving graininess by diffusion of dyes improves the RMS (root mean square) granularity by using so-called dye diffusible type couplers as described in British Patent No. 2,080,640A but this method gives an unpleasant visual sensation as described hereinafter.
The inventors have made various investigations with respect to improving graininess and have found the following. When a non-diffusible type coupler which forms a properly smearing diffusible dye (hereinafter, the non-diffusible type coupler is simply referred to as a dye diffusible type coupler) is employed, the so-called RMS granularity (the RMS granularity is described in T. H. James, Theory of the Photographic Process, 4th Ed., page 619) is greatly improved. However, the positioning and development probability of silver halide particles occur in random course, the dye diffuses to smear the mixes with the neighboring dye or dyes, whereby the overlap of dye clouds becomes larger, thus randomly forming huge dye clouds. This is visually very unpleasant and the visual sensation of graininess is sometimes deteriorated.